Crude oil as delivered to the sales-point can contain a substantial quantity of water, as well as solid particulate material, such as sand or mud. The oil, water and sludge are in the form of an emulsion, and in some cases the emulsion may contain up to 90% water. It is necessary to break the emulsion in order to separate the oil from the water phase and sludge. Breaking the emulsion is a difficult procedure, requiring expensive and complicated processing equipment. In some cases the emulsion cannot completely be broken, with the result that the oil is relegated to secondary uses.
It is recognized that hydrocarbon contaminants, as well as inorganic contaminants, such as calcium or ferrous compounds, can accumulate in the well, in the rock around the well, and on the mechanical components of the well, as well as in pipelines and storage tanks for the crude oil. The hydrocarbon contaminants tend to bond the heavier inorganic contaminants to the well casing and other components of the well, and heavier agglomerated inorganic contaminants will also tend to settle to the bottom of the well as a sludge. In certain situations, the build-up of the contaminants may be so great that the well will plug.
In the past, it has been the general practice to treat a well with a mineral acid, such as hydrochloric acid or sulfuric acid, in an attempt to remove the inorganic deposits. The acid is either dumped or pumped into the wellhead or circulated into the well, pipeline, treating vessels or storage tanks, by auxiliary piping. While the acid will tend to remove the inorganic deposits or contamination from the well bore as well as from the mechanical components of the well, it is believed that the acid also promotes the oil/water/solid particle emulsion which is delivered to the wellhead.
Certain aqueous industrial and household cleaners, as well as laundry detergents, contain a mixture of enzymes and surfactants. The enzymes can include one or more of a combination of proteases, amylases, lipases, cellulases, and pectinases and serve to attack or degrade organics such as grease, oil, or other soil, while the surfactant acts to disperse the degraded particles in the aqueous phase. Surfactants contain both hydrophilic and oleophilic groups, and according to the dispersion mechanism, an oleophilic group on the surfactant will attach to a particle of the oil, grease, or other soil, and pull it into dispersion by the attraction of the surfactant's hydrophilic group, for the water with which it is added. The dispersion is maintained by the action of the surfactant's hydrophilic groups. The hydrophilic groups on different surfactant molecules repel each other which necessarily results in the repulsion between the particles of oil, grease, and soil.
One type of industrial use of cleaning compositions of this type containing enzymes and a surfactant is to remove soiled lubricant from industrial machinery. In this manner of treatment, the aqueous cleaning composition containing a surfactant and enzymes is impinged on the surface to be treated through high pressure hoses or jets, and the residual wash water contains the soiled lubricant consisting of oil, grease, dirt, metal chippings, and the like, which are dispersed throughout the aqueous cleaning composition.
It has also been recognized, as disclosed in U.S. Pat. No. 5,459,066 that the addition of an amine oxide surfactant and enzymes to oily waste water will result in the separation of an oil phase from the water phase when the waste water is permitted to stand in a quiescent state.